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(11) | EP 1 801 784 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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Audio signal encoding and decoding device, method, program and recording medium Vorrichtung, Verfahren, Programm und Aufzeichnungsmedium für die Audiosignalkodierung und -dekodierung Dispositif, procédé, programme et dispositif d'enregistrement de codage et décodage de signal audio |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to a signal encoding device and a signal encoding method, a signal decoding device and a signal decoding method, a program, and a recording medium suitably applicable to expand a time-series signal limited to a frequency band at an encoding side to wider frequency band at a decoding side.
2. Description of the Related Art
[0002] In recent years, it has become possible to compress a tone quality corresponding to a CD (Compact Disc) in data amount of approximately 1/10 of the original CD by using a human's auditory structure in high-efficiency encoding of an audio signal. Products manufactured by using the technology are presently widespread in the market. Recording in a smaller recording medium or transmission through a network is actually performed.
[0003] In this high-efficiency compression, independent formats are respectively applied. It is possible to with any degree of freedom control the tone quality and a bit rate at an encoding side within the format range. For example, a mini disc (Mini Disc; MD) (Registered Trademark of Sony Corporation) includes two modes such as LP2 and LP4 to which a same high-efficiency compression technology is applied, as a long-time recording mode. LP4 is compressed to half the compression size with respect to LP2. Accordingly, LP4 has a deteriorated tone quality, but LP4 has a recording time twice that of the LP2.
[0004] However, the high-efficiency compression technology is designed and standardized by targeting the definite bit rate and tone quality. Therefore, when the standard (format) is maintained and the bit rate is reduced, the tone quality is drastically deteriorated. Generally, there is provided a method of distributing remained bits to a low-frequency signal by modifying a high-efficiency encoding algorithm at the encoding side and limiting a high-frequency signal so as to solve the problem.
[0005] "Information technology--Coding of audio-visual objects - Part 3: Audio (ISO/IEC 14496-3: 2001)" can be cited as a related art.
[0006] From US 2005/0004793 A1, a signal adaptation for higher band coding in a codec utilizing band split coding is known. A bandwidth extension algorithm is adjusted by adapting one or more of enhancing perception parameters of a high-band signal which is based on the characteristics of the input signal. Furthermore, an including performance in a low band with a codec utilizing audio-band split coding by separate encoders and decoders for each audio band is known.
SUMMARY OF THE INVENTION
[0007] As described above, when a high-frequency signal is limited to maintain tone quality and reduce a bit rate with the format unchanged, the high-frequency signal may be reproduced at a decoding side. For example, there are provided a technology for doubling a reproduction bandwidth of a PCM (Pulse Code Modulation) signal of 44.1 kHz sampling rate disclosed in Japanese Patent Unexamined Publication No. 2-311006 and a technology for expanding a frequency band of a phone disclosed in Japanese Patent Unexamined Publication No. 9-55778 at a receiving side.
[0008] This technology has an advantage that the problem can be solved by modifying only the decoding side without changing the format. However, since it is necessary to expand the bandwidth of only received signal, a dramatic effect is not shown in tone quality. High-frequency auditory distortion may sing in the ears regardless of a low frequency and a high frequency depending on input sound sources.
[0009] The bandwidth may be expanded by encoding information to expand the bandwidth at the encoding side by expanding the format and by using the information to expand the band at the decoding side. For example, there are provided a technology for expanding the bandwidth by using an LPC (Linear Predictive Coding) filter disclosed in U.S. Patent No. 5,068,899 and a technology for expanding the bandwidth by using a subband filter bank and a nonlinear device disclosed in U.S. Patent No. 5,127,054.
[0010] When this technology is used, an improvement effect can be obtained with respect to a sound signal. However, since the auditory distortion sings in the ears, a good quality cannot be obtained with respect to an audio signal. On the contrary, the good quality can be obtained with respect to the audio signal by using another technology to some extent. For example, the good quality can be, to some extent, obtained with respect to the audio signal in ISO standard HE-AAC (ISO/IEC 14496-3: 2001).
[0011] Fig. 10 shows an example of a configuration of a signal decoding device which performs a bandwidth expanding operation by HE-AAC. In a signal decoding device 100 shown in Fig. 10, a demultiplexing circuit 101 divides compressed data output from a signal encoding device into low-frequency information and high-frequency information, and provides the low-frequency information and the high-frequency information to a low-frequency information decoding circuit 102 and a bandwidth expanding circuit 104, respectively.
[0012] The low-frequency information decoding circuit 102 decodes the low-frequency information, generates low-frequency time-series signal, and provides the low-frequency time-series signal to a subband partitioning filter bank 103.
[0013] The subband partitioning filter bank 103 partitions the low-frequency time-series signal into plural bands (subbands), generate, and provides the low-frequency subband signal to the high-frequency expanding circuit 104 and a subband synthesizing filter bank 105.
[0014] The bandwidth expanding circuit 104 generates the high subband signal by using the high-frequency information and expands the bandwidth. More specifically, the high-frequency information includes the gain value of the high-frequency subband signal and the bandwidth expanding circuit 104 controls the gain of the high-frequency subband signal generated from the low-frequency subband signal by using the high-frequency information. Then, the bandwidth expanding circuit 104 provides the generated high-frequency subband signal to the subband synthesizing filter bank 105.
[0015] The subband synthesizing filter bank 105 synthesizes the low-frequency subband signal and the high-frequency subband signal, and generates the time-series signal as an output signal.
[0016] The above-mentioned high-frequency information is the gain value of the high-frequency subband signal. The gain value is acquired by each short-time sector (subframe) of the subband signal in the signal encoding device. Moreover, a difference value of the gain value is acquired in a frequency direction or in a time direction to improve an encoding efficiency. Therefore, any one of both directions can be selected by frames. For example, when the frequency direction is selected as a difference value acquiring direction in a frame, the difference value with the gain value of a subband at a low-frequency side adjacent to a low frequency from a high frequency side is acquired. As the result, since there is not provided a subband at the adjacent low-frequency side with respect to a first high-frequency subband which has a lowest frequency in the high-frequency subband signal, the gain value is the absolute value, but the gain value is the difference value after a second high-frequency subband. On the contrary, when the time direction is selected as the difference value acquiring direction, the gain value of each subband is the difference value from the gain value of a preceding time sector. Accordingly, the gain value of an optional initial time sector is the difference value from a final time sector of a preceding frame.
[0017] In the signal encoding device, the difference value acquiring direction is selected in consideration of a deflection of a time frequency signal by using the method. When the difference value is acquired, a code amount can decrease by using a variable-length code to reduce the deflection of the gain value.
[0018] However, when the frequency direction is selected as the difference value acquiring value, the gain value of the first high-frequency subband which has the lowest frequency in the high-frequency subband signal is the absolute value. Therefore, the code amount of the frame increases. When the time direction is selected as the difference value acquiring direction, it is difficult to treat an editing operation of the compressed data (bit stream) or a missing of information on a transmission line.
[0019] In the above circumstance, it is desirable that the invention provides a signal encoding device and a signal encoding method capable of effectively transmitting gain information of a high-frequency signal included in characteristic information of a high-frequency signal, a signal decoding device and a signal decoding method decoding compressed data output from the signal encoding device, and a program executing the signal encoding process and the signal decoding in a computer and a computer-readable recording medium in which the program is recorded.
[0020] According to the invention there are provided a coding and decoding device as set forth in claim 1 and 9 respectively, a coding and decoding method as set forth in claims 6 and 12, a coding and decoding program as set forth in claims 7 and 13, as well as a computer readable recording medium comprising the respective coding and decoding program as set forth in claims 8 and 14. Preferred embodiments are set forth in the dependent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021]
Fig. 1 is a schematic view of a signal encoding device according to an example.
Fig. 2 is a graph showing a band expansion by using a frequency aliasing method.
Fig. 3 shows an example of the grouping of high-frequency subband signal gain information in a grouping information generating circuit of a signal encoding device.
Fig. 4 shows an example of a method of acquiring low-frequency reference value information generated from a reference value information generating circuit of a signal encoding device and a difference in a high-frequency subband signal gain difference information generating circuit.
Fig. 5 shows an example of high-frequency gain offset information in a high-frequency gain difference information generating circuit in a signal encoding device.
Fig. 6 shows a power spectrum of high-frequency gain information and a signal of each subframe and each subband of a frame when a part of a subband signal is missed.
Fig. 7 shows another example of a method of acquiring low-frequency reference value information generated in a low-frequency reference value information generating circuit of a signal encoding device and a difference value in a high-frequency gain difference information generating circuit.
Fig. 8 is a schematic view for a configuration of a signal decoding device according to an embodiment of the invention.
Fig. 9 shows an example the smoothing in a high-frequency generating circuit of a signal decoding device.
Fig. 10 shows an example of the configuration of a single decoding device which performs a band expansion by HE-AAC.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0022] Hereinafter, detailed embodiments of the invention will be described with reference to the accompanying drawings.
[0023] First, Fig. 1 is a schematic view of a signal encoding device according to an example. As shown in Fig. 1, a signal encoding device 10 in this example includes a subband partitioning filter bank 11, a low-frequency encoding circuit 12, a high-frequency gain information generating circuit 13, a smoothing method selection information generating circuit 14, a grouping information generating circuit 15, a low-frequency reference value information generating circuit 16, a high-frequency gain difference information generating circuit 17, a quantization step information generating circuit 18, a high-frequency gain difference information encoding circuit 19, and a multiplexing circuit 20.
[0024] The subband partitioning filter bank 11 partitions an input time-series signal into plural subbands, and provides a low-frequency subband signal including plural low-frequency subbands to the low-frequency encoding circuit 12, the high-frequency gain information generating circuit 13, and the low-frequency reference value information generating circuit 16. In addition, the subband partitioning filter bank 11 provides high-frequency subband signal including plural high-frequency subbands to the high-frequency gain information generating circuit 13.
[0025] Herein, the subband signal is represented in x (k, n) (k=0, 1, 2,...N-1). k represents a subband index and N represents the number of partitioned subbands. In addition, n represents a time index. When the subband at k=0 is a lowest-frequency subband and the subband at k=N-1 is the highest-frequency subband, the entire subband signal at k=0, 1, ..., N/2-1 is the low-frequency subband signal and the entire subband signal at k=N/2, N/2+1, ..., N-1 is the high-frequency subband signal in the subband partitioning filter bank 11.
[0026] In this example, the number of the subbands is N/2 at both a low-frequency side and a high-frequency side, but the ratio of the number of the low-frequency subbands and the number of high-frequency subbands can be optionally set and the numbers of both subbands need not be the same.
[0027] The low-frequency encoding circuit 12 quantizes and encodes the low-frequency subband signal, and provides low-frequency encoding data to the multiplexing circuit 20.
[0028] The high-frequency gain information generating circuit 13 calculates an average gain value by short-time sector (subframes) with respect to the high-frequency subband signal and generates high-frequency gain information. The high-frequency gain information generating circuit 13 provides the generated high-frequency gain information to the smoothing method selection information generating circuit 14, the grouping information generating circuit 15, and the low-frequency reference value information generating circuit 16.
[0029] Hereinafter, a method of generating the high-frequency gain information by using the high-frequency gain information generating circuit 13 will be described.
[0030] Herein, in this example, expanding the bandwidthat a decoding side is performed by using a frequency aliasing method disclosed in U.S. Patent No. 5,068,899. In this frequency aliasing method, the low-frequency subband signal is reversed in frequency at the decoding side to generate the high-frequency subband signal. That is, when the low-frequency subband signal at the decoding side is x'(k, n) (k=0, 1, ..., N/2-1) and the high-frequency subband signal generated from the low-frequency subband signal is xa (i, n) (i=N-k-1), x' (k, n) and xa(i, n) have the relation shown in Equation (1).
[0031] The low-frequency subband signal x'(k, n) shown in Equation (1) includes a quantization error caused by the low-frequency encoding circuit 12 with respect to the original low-frequency subband signal x(k, n) at the encoding side.
[0032] Fig. 2 is a graph showing a band expansion by the frequency aliasing method. As shown in Fig. 2, the subband signal reverses in N/2th subband in case of using the frequency aliasing method. Therefore, for example, the low-frequency subband signal at k=0 becomes the high-frequency subband signal at i=N-1 and the low-frequency subband signal at k=2 becomes the high-frequency subband signal at i=N-3.
[0033] At a decoder, the high-frequency subband signal xa(i, n) is generated from the low-frequency x' (k, n) (k=0, 1, ..., N/2-1). The original high-frequency subband signal x(k, n) (k=N/2, N/2+1, ..., N-1) at the encoder and xa(i, n) generated according to Equation (1) described above have a different gain in each subband.
[0034] Accordingly, at the decoder, it is necessary to control the gain of the high-frequency subband signal xa (i, n) having an expanded band according to Equations (2) and (3) shown below.
[0035] In Equation (3), B represents a sample period and g(i) represents a gain control value in a subframe of the sample period B from a sample b. In addition, eh(i) represents high-frequency gain information in the subframe of the sample period B from the sample b. eh (i) is calculated at the encoder and is acquired on the basis of information transmitted to the decoder. The above-mentioned high-frequency gain information generating circuit 13 generates the high-frequency gain information eh(i) from the high-frequency subband singal according to Equation (4) shown below, and supplying the generated high-frequency gain information eh (i) to the selection information generating circuit 14, the grouping information generating circuit 15 and the low-frequency reference value information generating circuit 16.
[0036] However, since the high-frequency gain information accounts for large ratio in the low-frequency encoding data out of the compressed data output from the multiplexing circuit 20 of the signal encoding device 10, it is important to minimize the deterioration of the tone quality and reduce an information amount.
[0037] Therefore, in the signal encoding device 10 of this example, the amount of the high-frequency gain information is reduced by using methods (a) to (c) as described below.
- (a) In the grouping information generating circuit 15, the sample period B is variable when the high-frequency gain information is acquired according to Equation (3).
- (b) In the high-frequency gain difference generating circuit 17, a difference value with the high-frequency gain information is acquired in a frequency direction of a low frequency to a high frequency, specifically, at a time position corresponding to an adj acent low-frequency subband with respect to the high-frequency gain information acquired by each subband and by each subframe. Low-frequency subbands adjacent to the lowest-frequency subbands in the high-frequency subband signal is not provided, but the difference value with a low-frequency reference value acquired from the low-frequency subband signal is acquired in the low-frequency reference value information generating circuit 16 to prevent an absolute value from being generated.
- (c) In the high-frequency gain difference information encoding circuit 19, the difference value of the high-frequency gain information is quantized by a quantization step value generated in the quantization step information generating circuit 18 and the quantized difference value is encoded by using a fixed-length code or a variable-length code.
[0038] Referring back to Fig. 1, the smoothing method selection information generating circuit 14 generates the smoothing method selection information on the basis of the high-frequency gain information and provides the generated smoothing method selection information to the multiplexing circuit 20. Smoothing is not performed at the encoder, but is performed at the decoder on the basis of the smoothing method selection information. The smoothing method selection information includes information about smoothing or not. In addition, the smoothing method selection information further includes information a smoothing function (for example, a sinewave or a linear function) used at the time of performing the smoothing. For example, when discontinuity points increase in the high-frequency subband signal in which the band is expanded at the decoder, the smoothing in the time direction is performed by using the sinewave, that is, the smoothing method can be adaptively selected by frames.
[0039] The grouping information generating circuit 15 determines the sample period in which the above-mentioned high-frequency gain information is acquired. More specifically, the grouping information generating circuit 15 groups a steady part with a timely change of the high-frequency gain information, and calculates the high-frequency gain information of each group again. Grouping information determined therein is the high-frequency gain grouping information and the high-frequency gain information calculated by each group is the high-frequency grouping gain information. The grouping information generating circuit 15 provides the high-frequency grouping gain information to the high-frequency gain difference information generating circuit 17 and provides the high-frequency gain grouping information to the low-frequency reference value information generating circuit 16 and the multiplexing circuit 20.
[0040] Fig. 3 shows an example of the grouping of the high-frequency gain information in the grouping information generating circuit 15. In addition, Fig. 3 shows the high-frequency gain information in each subframe and in each subband of the frame at the time of analyzing the subband signal. Each frequency band at a longitudinal axis represents the subband. In Fig. 3, four subbands at the low-frequency side constitute a low-frequency subband 31 and five subbands at the high-frequency side constitute a high-frequency subband 32. However, this example may not be applied. Hereinafter, the lowest-frequency subband out of the high-frequency subbands 32 is called a first high-frequency subband. As the frequency increases, the high-frequency subbands are called a second high-frequency subband and a third high-frequency subband. Each time sector at a horizontal axis represents the subframe. In Fig. 3, the subframe is grouped by two subframes, three subframes, and three subframes. The groups are called a first group 33, a second group 34, and a third group 35, respectively.
[0041] In the grouping information generating circuit 15, the high-frequency gain information 36 of the first subframe and the high-frequency gain information 37 of the second subframe in the first high-frequency subband are grouped and recalculated. Therefore, the grouped and recalculated high-frequency gain information become one high-frequency grouping gain information 38. Similarly, the high-frequency gain information 39 of the first subframe and the high-frequency gain information 40 of the second subframe in the second high-frequency subband are grouped and recalculated. Therefore, the grouped and recalculated high-frequency gain information become one high-frequency grouping gain information 41.
[0042] As described above, this grouping is generally performed in consideration of the timely steadiness of the high-frequency subband signal. For example, with respect to eh(i) acquired in Equation (4), an average value of the entire high-frequency subband of each subframe is acquired. Then, when a difference between the subframes is within a threshold value, the grouping is performed.
[0043] In Fig. 3, grouping the high-frequency gain information in the first high-frequency subband and the second high-frequency subband is performed on the basis of a same high-frequency gain grouping information. However, different high-frequency gain grouping information may be used by plural subbands.
[0044] In the example described above, the high-frequency gain grouping information is determined from only the high-frequency gain information. However, the high-frequency gain grouping information maybe determined by using the low-frequency subband signal, for example, by adding a gain control amount shown in Equation (3).
[0045] Referring back to Fig. 1, the low-frequency reference value information generating circuit 16 generates the low-frequency reference value information on the basis of the high-frequency gain information, the high-frequency gain grouping information, and the low-frequency subband signal. Then, in the low-frequency reference value information generating circuit 16, a method of generating the low-frequency reference value information can be adaptively selected as described below. The low-frequency reference value information generating circuit 16 provides the low-frequency reference value information to the high-frequency gain difference information generating circuit 17 and provides the low-frequency reference value selection information representing a method of generating the selected low-frequency reference value information to the multiplexing circuit 20.
[0046] The high-frequency gain difference information generating circuit 17 acquires a difference value in a frequency direction of the high-frequency grouping gain information and generates the high-frequency gain difference information. Then, the high-frequency gain difference information generating circuit 17 acquires the difference value with the low-frequency reference value with respect to the high-frequency grouping gain information in the first high-frequency subband. The high-frequency gain difference information generating circuit 17 generates high-frequency gain offset information as necessary. The high-frequency gain difference information generating circuit 17 provides the high-frequency gain difference information to the quantization step information generating circuit 18 and the high-frequency gain difference information encoding circuit 19. In addition, the high-frequency gain difference information generating circuit 17 provides the high-frequency gain offset information to the multiplexing circuit 20.
[0047] Detailed process in the low-frequency reference value information generating circuit 16 and the high-frequency gain difference information generating circuit 17 will be described below.
[0048] The quantization step information generating circuit 18 generates quantization step information on the basis of the high-frequency gain difference information and provides the generated quantization step information to the high-frequency gain difference information encoding circuit 19 and the multiplexing circuit 20.
[0049] The high-frequency gain difference information encoding circuit 19 quantizes and encodes the high-frequency gain difference information on the basis of the quantization step information, and generates high-frequency gain difference information encoding data. The high-frequency gain difference information encoding circuit 19 provides the high-frequency gain difference information encoding data to the multiplexing circuit 20.
[0050] Themultiplexingcircuit 20multiplexes the low-frequency encoding data, the low-frequency reference value selection information, the high-frequency gain grouping information, the smoothing method selection information, the quantization step information, and the high-frequency gain difference information encoding data. In addition, the multiplexing circuit 20 multiplexes the high-frequency gain offset information as necessary, and generates and output the compressed data.
[0051] Herein, the process in the above-mentioned low-frequency reference value information generating circuit 16 and the high-frequency gain difference information generating 17 will be specifically described.
[0052] Fig. 4 shows an example of a method of acquiring the low-frequency reference value information generated by the low-frequency reference value information generating circuit 16 and the difference value in the high-frequency gain difference information generating circuit 17. In addition, Fig. 4 shows the high-frequency grouping gain information in each subframe and in each subband of a frame. Similar to Fig. 3, In Fig. 3, four subbands at the low-frequency side constitute the low-frequency subband 31 and five subbands at the high-frequency side constitute the high-frequency subband 32. Similar to Fig. 3, the information is grouped by the first group 33, the second group 34, and the third group 35, respectively.
[0053] As described above, in the low-frequency reference value information generating circuit 16, a method of generating the low-frequency reference value information can be selected. Fig. 4 shows an example calculating the low-frequency reference value information of each group. That is, in the first group 33, low-frequency reference value information 42 is calculated from the low-frequency subband signal including four subbands and two subframes. Similarly, low-frequency reference value information 43 is calculated in the second group 34 and low-frequency reference value information 44 is calculated in the third group 35. The low-frequency reference value information can be calculated according to, for example, Equation (5) shown below.
lowabs shown in Equation (5) represents the low-frequency reference value. sb represents the first high-frequency subband and sb-1 represents the highest-frequency subband in the low-frequency subband signal. C represents a time period determined by the high-frequency gain grouping information, for example, the time period corresponding to two subframes in the first group 33.
[0054] The method of calculating the low-frequency reference value information of each group is not limited to Equation (5) shown above and a same calculating method may be used at both the encoder and the decoder. For example, as shown in Equation (6), the low-frequency reference value information may be calculated from the highest-frequency subband sb-1 in the low-frequency subband signal.
[0055] Since the relativity of the gain value between the subband sb-1 and the subband sb is comparatively high in the calculating method shown in Equation (6), the calculating method is suitable for acquiring the difference value in the high-frequency gain difference information generating circuit 17. However, since the low-frequency reference value information of the encoder and the low-frequency reference value information of the decoder may be different due to the influence a quantization error of the low-frequency subband signal, the calculating method is suitable for assigning sufficient amount of bits at the time of encoding the low-frequency subband signal.
[0056] In the calculating method in Equation (5) shown above, since a variation of the low-frequency reference value caused by the influence of the quantization error decreases compared in the case of that in Equation (6), but an audio signal generally as a power as large as the low-frequency subband, the high-frequency gain difference information in the subband sb increases. In this case, when the difference is acquired through the high-frequency gain offset information common to all groups at the time of calculating the difference value, the encoding efficiency is improved. The high-frequency gain offset information will be specifically in the description of the high-frequency gain difference information generating circuit 17.
[0057] The high-frequency gain difference information generating circuit 17 generates the high-frequency gain difference information by each group.
[0058] In Fig. 4, first, the high-frequency gain information 38 in the first group of the first high-frequency subband is subtracted from the low-frequency reference value information 42 of the first group 33 and becomes the high-frequency gain difference information. Similarly, the high-frequency gain difference information is calculated in the second group 34 and the third group 35.
[0059] Herein, when the low-frequency reference value information is calculated according to Equation (5) shown above, the high-frequency gain difference information in the first high-frequency subband may increase. Therefore, it is preferable to acquire the difference value through the high-frequency gain offset information common to each group so as to improve the encoding efficiency. As shown in the example of Fig. 5, the high-frequency gain offset information can be represented in bits of table. For example, when the difference values of the first to third groups 33 to 35 are -20 dB, -16 dB, and -18 dB, respectively, the average value is -18 dB. Accordingly, the difference values of the high-frequency grouping gain information in the first high-frequency subband are represented in -2 dB, +2 dB, and 0 dB, respectively, by using the high-frequency gain offset information at ID=4 having a value closest to the average value. The selected high-frequency offset information is transmitted to the multiplexing circuit 20 and is used for generating the high-frequency grouping gain information at the decoder.
[0060] In Fig. 4, the high-frequency gain difference information 41 in the first group of the second high-frequency subband is subtracted from the high-frequency grouping gain information 38 in the first group of the first high-frequency subband and becomes the high-frequency gain difference information. The high-frequency gain difference information generating circuit 17 calculates the high-frequency gain difference information of each group and each subband as described above.
[0061] However, the method of acquiring the difference value of each group has an advantage in reducing the information amount, but the method also has a disadvantage in being weak at the variation of reduction reference value information at the encoder and the decoder. For example, a part of the subband signal may be missed due to the influence of the quantization error caused during encoding and decoding the low-frequency subband signal or depending on an upper limit of a given bit rate. In this case, the low-frequency reference value information is varied by each group.
[0062] As described above, Fig. 6A shows high-frequency gain information of each subframe and each subband of a frame when the part of the subband signal is missed. In addition, Fig. 6B shows a power spectrum of a signal corresponding to Fig. 6B. In Fig. 6A, four subbands at the low-frequency side constitute a low-frequency subband 51 and five subbands at the high-frequency side constitute a high-frequency subband 52. In Fig. 6A, the information is grouped by three subframes, one subframe, and four subframes. Hereinafter, the groups shown in Fig. 6A are called a first group 53, a second group 54, and a third group 55, respectively.
[0063] When the number of given bits decreases and it is judged that a band 57 shown in Fig. 6B is not auditorily important, a subband 56 corresponding to the band 57 may be missed. In this case, when the low-frequency reference value is calculated by groups, the variation of the low-frequency reference value increases in the second group 54 including only one subframe. That is, an effect extent of the subband 56 is significantly different by each group.
[0064] It is necessary to compensate the high-frequency gain information of each group by calculating a variation extent at the encoder during the encoding and decoding of the low-frequency subband signal so as to prevent the variation of the low-frequency reference value. In this case, the encoder includes a low-frequency subband signal encoding device. This is not preferable in an operation speed or a power consumption of the signal encoding device.
[0065] Therefore, the low-frequency reference value information generating circuit 16 may calculate one low-frequency reference value in the entire subband signal without using the high-frequency gain grouping information.
[0066] Fig. 7 shows the high-frequency gain information of each subframe and each subband of a frame in case of calculating one low-frequency reference value information in the entire low-frequency subband signal. In Fig. 7, four subbands at the low-frequency side constitute the low-frequency subband 31 and five subbands at the high-frequency side constitute the high-frequency subband 32, similar to Fig. 3. The information is grouped by the first group 33, the second group 34, and the third group 35, similar to Fig. 3.
[0067] In Fig. 7, the low-frequency reference value information generating circuit 16 calculates low-frequency reference value information 45 from the entire low-frequency subband signal. In addition, in the high-frequency gain difference information generating circuit 17, the high-frequency grouping gain information 38 in the first group of the first high-frequency subband is subtracted from the low-frequency reference value information 45 and become the high-frequency gain difference information. Similarly, the high-frequency gain difference information is calculated by using the same low-frequency reference value information 45 in the second group 34 and the third group 35.
[0068] As described above, the method of calculating one low-frequency reference value information in the entire low-frequency subband signal, the variation of the low-frequency reference value in each group becomes the same even in the case described in Fig. 6. Therefore, the relative relation of the gain of the high-frequency subband signal among the groups is maintained.
[0069] However, this method is not very preferable in the viewpoint of reducing the amount of the high-frequency gain information. For example, when an input signal has a pulse form, the first group 33 and the third group 35 may have a small gain, and the second group 34 may have a large gain. However, in this case, the difference value between the low-frequency reference value information 45 and each group in the first high-frequency subband is very large values such as, for example, -20 dB, +10 dB, and -20 dB. In case of the encoding by using the variable-length code, the length of the code is considerably increased.
[0070] In the method of calculating the low-frequency reference value information by each group by using the high-frequency gain grouping information, the high-frequency gain grouping information is not used. The method of calculating one low-frequency reference value information in the entire low-frequency subband signal without using the high-frequency gain grouping information has both the advantage and the disadvantage.
[0071] The low-frequency reference value information generating circuit 16 adaptively selects a method of generating the low-frequency reference value information on the basis of the nature of the input signal, that is, whether to calculate the low-frequency reference value information of each group or to calculate one low-frequency reference value information in the entire low-frequency subband signal. More specifically, the reference value information generating circuit 16 adaptively selects the method of generating the low-frequency reference value information in consideration of the quantization error of the low-frequency subband signal, a timely variation of a specific high-frequency subband signal or the entire high-frequency subband, and a difference in the code amounts of both methods.
[0072] More specifically, in case of selecting the method of generating the low-frequency reference value in consideration of the quantization error of the low-frequency subband signal, the quantization error can be estimated from a bit assignment amount of each low-frequency subband signal. Therefore, when it is judged that the power is considerably varied in the specific subband as shown in Fig. 6, the low-frequency reference value selection information is determined to calculate the low-frequency reference value information from the entire low-frequency subband signal as shown in Fig. 7. On the contrary, when the variation in power of the each subband is in the range of a threshold value, the low-frequency reference value selection information is determined to calculate the low-frequency reference value information by each group in the low-frequency subband signal as shown in Fig. 4.
[0073] In case of selecting the method of generating the low-frequency reference value in consideration of the timely variation of a specific high-frequency subband signal or the entire high-frequency subband signal, for example, when the timely variation increases, the low-frequency reference value information is calculated by each group. On the contrary, when the timely variation decreases, one low-frequency reference value information is calculated in the entire low-frequency subband signal. This method is very suitable for a small-sized circuit of the signal encoding device.
[0074] In the signal encoding device having a large-sized circuit, both of two generating methods shown in Fig. 4 and Fig. 7 are performed. Therefore, one method having the smaller final code amount of high-frequency subband signal gain difference information encoding data may be selected.
[0075] The low-frequency reference value selection information may be determined by comprehensively judging the method in which the quantization error of the low-frequency subband signal, or the timely variation of the specific high-frequency subband signal or the entire high-frequency subband signal is considered, and the method in which the difference in code amount of the specific high-frequency subband signal and the entire high-frequency subband signal is considered.
[0076] In the method of calculating the low-frequency reference value information, the optimal method can be selected in consideration of a desired tone quality, a circuit size of the signal encoding device, or the like.
[0077] Next, Fig. 8 is a schematic view of a signal decoding device according to an example. As shown in Fig. 8, a signal decoding device 60 of this example includes a demultiplexing circuit 61, a low-frequency decoding circuit 62, a low-frequency reference gain value information generating circuit 63, a high-frequency gain difference information generating circuit 64, a high-frequency grouping gain information generating circuit 65, a high-frequency generating circuit 66, and a subband synthesizing filter bank 67.
[0078] The demultiplexing circuit 61 demultiplexes an input compressed data and provides the low-frequency encoding data to the low-frequency decoding circuit 62. The demultiplexing circuit 61 provides the high-frequency gain difference information encoding data and the quantization step information to the high-frequency gain difference information generating circuit 64, and provides the smoothing method selection information to the high-frequency generating circuit 66. The demultiplexing circuit 61 provides the high-frequency gain grouping information to the low-frequency reference value information generating circuit 63 and the high-frequency generating circuit 66, and provides the low-frequency reference value selection information to the low-frequency reference value information generating circuit 63. When the compressed data includes the high-frequency gain offset information, the demultiplexing circuit 61 provides the information to the high-frequency grouping gain information generating circuit 65.
[0079] The low-frequency decoding circuit 62 decodes and unquantizes the low-frequency encoding data, and provides the low-frequency subband signals which are the signals of plural low-frequency subbands to the low-frequency reference value information generating circuit 63, the high-frequency generating circuit 66, and the subband synthesizing filter bank 67.
[0080] The low-frequency reference value information generating circuit 63 generates the low-frequency reference value information similar as the encoder on the basis of the low-frequency subband signal, the high-frequency gain grouping information, and the low-frequency reference value selection information, and provides the generated low-frequency reference value information to the high-frequency grouping gain information generating circuit 65.
[0081] The high-frequency gain difference information generating circuit 64 decodes and unquantizes the high-frequency gain difference information encoding data on the basis of the quantization step information, and generates the high-frequency gain difference information. The high-frequency gain difference information generating circuit 64 provides the generated high-frequency gain difference information to the high-frequency grouping gain information generating circuit 65.
[0082] The high-frequency grouping gain information generating circuit 65 generates the high-frequency gain information on the basis of the high-frequency gain difference information and the low-frequency reference value information, and as necessary the high-frequency gain offset information. The high-frequency grouping gain information generating circuit 65 provides the generated high-frequency gain information to the high-frequency generating circuit 66.
[0083] The high-frequency generating circuit 66 generates the high-frequency subband signal on the basis of the low-frequency subband signal, the high-frequency gain information, the smoothing method selection information, and the high-frequency gain grouping information, and provides the generated high-frequency subband signal to the subband synthesizing filter bank 67. More specifically, the high-frequency generating circuit 66 generates the high-frequency subband signal in a same method as the method described in Fig. 2 and Equations (1) to (3) described above.
[0084] However, when a smoothing method at a time axis is designated by the smoothing method selection information, the high-frequency generating circuit 66 smoothes the high-frequency gain information on the basis of the smoothing method selection information. For example, when a smoothing performed by a sinewave function is designated, the smoothing is performed as shown in Fig. 9. In Fig. 9, when the gain control values of the first subframe and the second subframe in a high-frequency subband are g(0) and g(1), respectively, a smoothing function gsm(n) is acquired according to Equations (7) to (9) shown below.
[0085] The high-frequency generating circuit 66 generates the high-frequency subband signal according to Equation (10) shown below instead of Equation (2) by using the smoothing function gsm(n) acquired as described above.
[0086] By this method, the smoothing at the time axis is similarly performed with all the subframes and subbands.
[0087] Referring back to Fig. 8, the subband synthesizing filter bank 67 synthesizes the low-frequency subband signal and the high-frequency subband signal, and outputs the acquired time-series signal.
[0088] As described above, in the signal encoding device 10 and the signal decoding device 60 according to this example, it is possible to minimalize a disadvantage in acquiring the difference value of the high-frequency gain information and improve the encoding efficiency. Especially, in the signal encoding device 10 and the signal decoding device 60 according to this example, since the difference value between the high-frequency gain information in the lowest-frequency subband in the high-frequency subband signal and the low-frequency reference value information is acquired, the absolute value is not generated in the frame. Moreover, the gain of the high-frequency subband signal is generally acquired from the low-frequency reference value information generated on the basis of the low-frequency subband signal, the balance in timely variation of the high-frequency subband signal and the low-frequency subband signal is excellent. Therefore, the time-series signal having very little confliction can be generated after the subbands are synthesized.
[0089] In the example described above, the method of generating the high-frequency subband signal from the low-frequency subband signal by using the frequency aliasing method. However, the method of generating the high-frequency subband signal from the low-frequency subband signal is not limited to the frequency aliasing method. Therefore, for example, a frequency shift method described in U.S. Patent No. 466,730 may be used as the method of generating the high-frequency subband signal from the low-frequency subband signal.
[0090] The example described above is described by using the configuration of hardware, but the example is not limited to the configuration of the hardware. An optical process can be performed by executing a computer program with a CPU (Central Processing Unit). In this case, the computer program which is stored in a recording medium may be provided. In addition, the computer program may be provided through transmission media including Internet.
partitioning means (11) for partitioning the time-series signal into plural subbands to generate a low-frequency subband signal including plural low-frequency subbands and a high-frequency subband signal including plural high-frequency subbands;
low-frequency encoding means (12) for quantizing and encoding the low-frequency subband signal to generate low-frequency encoding data;
high-frequency gain information generating means (13) for generating high-frequency gain information by generating a new high-frequency subband signal from the low-frequency subband signal and controlling the gain of the new high-frequency subband signal generated from the low-frequency subband signal using the gain value of the high-frequency information for each subband at a predetermined time interval;
low-frequency reference gain value information generating means (16) for generating low-frequency reference gain value information on the basis of at least the low-frequency subband signal;
high-frequency gain difference information generating means (17) for generating high-frequency gain difference information by acquiring a difference value between the high-frequency gain information generated in each subband at a predetermined time interval and the high-frequency gain information of an adjacent low-frequency subband at a corresponding time position corresponding to an adjacent low-frequency subband, and acquiring a difference value between high-frequency gain information of a lowest-frequency subband in the high-frequency subband signal and the low-frequency reference gain value information;
high-frequency gain difference information encoding means (19) for quantizing and encoding the high-frequency gain difference information to generate high-frequency gain difference information encoding data;
multiplexing means (20) for multiplexing at least the low-frequency encoding data and the high-frequency gain difference information encoding data to output the multiplexed data as compressed data;
grouping information generating means (15) for generating high-frequency grouping gain information of each group and generating high-frequency gain grouping information about a grouping method by grouping the high-frequency gain information generated in each subband at a predetermined time interval by plural groups in a time direction,
wherein the high-frequency gain difference information generating means is adapted to generate the high-frequency gain difference information by acquiring a difference value with high-frequency grouping gain information at an adjacent low-frequency subband at a corresponding time position, and the multiplexing means further is adapted to multiplex the high-frequency gain grouping information;wherein the low-frequency reference gain value information generating means is adapted to generate low-frequency reference gain value information about a selected generating method with the low-frequency reference gain value information by adaptively selecting either the method of generating low-frequency reference gain value information from the entire low-frequency subband signal or a method of generating the low-frequency reference gain value information by groups from the low-frequency subband signal on the basis of the high-frequency gain grouping information, and the multiplexing means further is adapted to multiplex the low-frequency reference gain value selection information.
wherein the low-frequency reference gain value information generating means (16) selects one of the method of generating the low-frequency reference gain value information from the entire low-frequency subband signal and the method of generating the low-frequency reference gain value information by groups from the low-frequency subband signal, on the basis of a quantization error of the low-frequency subband signal.
wherein the low-frequency reference information generating means (16) selects one of the method of generating the low-frequency reference gain value information from the entire low-frequency subband signal and the method of generating the low-frequency reference gain value information by groups from the low-frequency subband signal to reduce a code amount of the high-frequency gain difference information.
quantization step information generating means (18) for generating quantization step information at the time of quantizing the high-frequency gain difference information on the basis of the high-frequency gain difference information,
wherein the multiplexing means (20) further multiplexes the quantization step information.smoothing method selection information generating means (14) for generating smoothing method selection information about a method of smoothing the high-frequency subband signal generated at a decoding side in a time direction on the basis of the high-frequency gain information,
wherein the multiplexing means (20) further multiplexes the smoothing method selection information.partitioning the time-series signal into plural subbands and generating a low-frequency subband signal including plural low-frequency subbands and a high-frequency subband signal including plural high-frequency subbands;
quantizing and encoding the low-frequency subband signal to generate low-frequency encoding data;
generating high-frequency gain information by generating a new high-frequency subband signal from the low-frequency subband signal and controlling the gain of the new high-frequency subband signal generated from the low-frequency subband signal using the gain value of the high-frequency information for each subband at a predetermined time interval;
generating low-frequency reference gain value information on the basis of at least the low-frequency subband signal;
generating high-frequency gain difference information by acquiring a difference value between the high-frequency gain information generated in each subband at a predetermined time interval and the high-frequency gain information of an adjacent low-frequency subband at a corresponding time position corresponding to an adjacent low-frequency subband, and acquiring a difference value between a high-frequency gain information of a lowest-frequency subband in the high-frequency subband signal and the low-frequency reference gain value information;
quantizing and encoding the high-frequency gain difference information to generate high-frequency gain difference information encoding data;
multiplexing at least the low-frequency encoding data and the high-frequency gain difference information encoding data to output the multiplexed data as compressed data;
generating high-frequency grouping gain information of each group and generating high-frequency gain grouping information about a grouping method by grouping the high-frequency gain information generated in each subband at a predetermined time interval by plural groups in a time direction,
generating the high-frequency gain difference information by acquiring a difference value with high-frequency grouping gain information at an adjacent low-frequency subband at a corresponding time position, and further multiplexing the high-frequency gain grouping information;
wherein the low-frequency reference gain value information about a selected generating method is generated by adaptively selecting either the method of generating low-frequency reference gain value information from the entire low-frequency subband signal or a method of generating the low-frequency reference gain value information by groups from the low-frequency subband signal on the basis of the high-frequency gain grouping information, and the low-frequency reference gain value selection information is multiplexed.demultiplexing means (61) for demultiplexing the compressed data to generate low-frequency encoding data and high-frequency gain difference encoding data;
low-frequency decoding means (62) for decoding and unquantizing the low-frequency encoding data to generate low-frequency subband signal;
low-frequency reference gain value information generating means (63) for generating low-frequency reference gain value information on the basis of at least the low-frequency subband signal;
high-frequency gain difference information generating means (64) for generating high-frequency gain difference information of each subband at a predetermined time interval by decoding and unquantizing the high-frequency gain difference information encoding data;
high-frequency gain information generating means (65) for generating high-frequency gain information on the basis of high-frequency gain difference information of an adjacent subband at a corresponding time position and generating high-frequency gain information on the basis of the low-frequency reference gain value information in a lowest-frequency subband out of the high-frequency subband signals;
high-frequency generating means (66) for generating the high-frequency subband signal from the low-frequency subband signal and controlling the gain of the high-frequency subband signal on the basis of the high-frequency gain information; and
synthesizing means (67) for synthesizing the low-frequency subband signal and the high-frequency subband signal having a controlled gain to output the synthesized signals as a time-series signal;
wherein the compressed data includes smoothing method selection information about a method of smoothing the high-frequency subband signal in a time direction; andwherein the high-frequency generating means controls the gain of the high-frequency subband signal generated from the low-frequency subband signal on the basis of the high-frequency gain information and the smoothing method selection information.
wherein the high-frequency gain difference information generating means (64) generates the high-frequency gain difference information by subbands and by groups by decoding and unquantizing the high-frequency gain difference information encoding data;
the high-frequency gain information generating means (65) generates high-frequency gain information on the basis of high-frequency gain difference information at an adjacent low-frequency subband at a corresponding time position and generates high-frequency gain information on the basis of the low-frequency reference gain value information of a lowest-frequency subband in the high-frequency subband signal; and
the high-frequency generating means (66) generates the high-frequency subband signal from the low-frequency subband signal and controls the gain of the high-frequency subband signal on the basis of the high-frequency gain information.
wherein the compressed audio data includes low-frequency reference gain value selection information about a method of generating the low-frequency reference gain value selection information; and
wherein the low-frequency reference gain value information generating means (63) selects one of a method of generating low-frequency reference gain value information from the entire low-frequency subband signal on the basis of the low-frequency reference gain value selection information and a method of generating the low-frequency reference gain value information of each group from the low-frequency subband signal on the basis of the high-frequency gain grouping information.
demultiplexing the compressed data to generate low-frequency encoding data and high-frequency gain difference encoding data;
decoding and unquantizing the low-frequency encoding data to generate low-frequency subband signal;
generating low-frequency reference gain value information on the basis of at least the low-frequency subband signal;
generating high-frequency gain difference information of each subband at a predetermined time interval by decoding and unquantizing the high-frequency gain difference information encoding data;
generating high-frequency gain information on the basis of high-frequency gain difference information of an adjacent subband at a corresponding time position and generating high-frequency gain information on the basis of the low-frequency reference gain value information of a lowest-frequency subband in the high-frequency subband signal;
generating the high-frequency subband signal from the low-frequency subband signal and controlling the gain of the high-frequency subband signal on the basis of the high-frequency gain information;
synthesizing the low-frequency subband signal and the high-frequency subband signal having a controlled gain to output the synthesized signals as a time-series signal;
with the compressed data including smoothing method selection information about a method of smoothing the high-frequency subband signal in a time direction; and
the high-frequency generating means controlling the gain of the high-frequency subband signal generated from the low-frequency subband signal on the basis of the high-frequency gain information and the smoothing method selection information.
einer Partitionierungseinrichtung (11) zum Partitionieren des Zeitreihensignals in mehrere Unterbänder zum Erzeugen eines Niederfrequenz-Unterbandsignals mit mehreren Niederfrequenz-Unterbändern und eines Hochfrequenz-Unterbandsignals mit mehreren Hochfrequenz-Unterbändern;
einer Niederfrequenz-Kodiereinrichtung (12) zum Quantisieren und Kodieren des Niederfrequenz-Unterbandsignals zum Erzeugen von Niederfrequenz-Kodierdaten;
einer Hochfrequenz-Verstärkungsinformation-Erzeugungseinrichtung (13) zum Erzeugen von Hochfrequenz-Verstärkungsinformation durch Erzeugen eines neuen Hochfrequenz-Unterbandsignals aus dem Niederfrequenz-Unterbandsignal und Steuern der Verstärkung des neuen Hochfrequenz-Unterbandsignals, das aus dem Niederfrequenz-Unterbandsignal erzeugt wurde, unter Verwendung des Verstärkungswerts der Hochfrequenzinformation für jedes Unterband zu einem zuvor festgelegten Zeitintervall;
einer Niederfrequenz-Referenzverstärkungswertinformation-Erzeugungseinrichtung (16) zum Erzeugen von Niederfrequenz-Referenzverstärkungswertinformation auf der Grundlage wenigstens des Niederfrequenz-Unterbandsignals;
einer Hochfrequenz-Verstärkungsdifferenzinformation-Erzeugungseinrichtung (17) zum Erzeugen von Hochfrequenz-Verstärkungsdifferenzinformation durch ein Einholen eines Differenzwerts zwischen der in jedem Unterband bei einem zuvor festgelegten Zeitintervall erzeugten Hochfrequenz-Verstärkungsinformation und der Hochfrequenz-Verstärkungsinformation eines angrenzenden Niederfrequenz-Unterbands bei einer entsprechenden Zeitposition, die einem angrenzenden Niederfrequenz-Unterband entspricht, und Einholen eines Differenzwerts zwischen einer Hochfrequenz-Verstärkungsinformation eines Niedrigst-Frequenz Unterbands in dem Hochfrequenz-Unterbandsignal und der Niederfrequenz-Referenzverstärkungswertinformation;
einer Hochfrequenz-Verstärkungsdifferenzinformation-Kodiereinrichtung (19) zum Quantisieren und Kodieren der Hochfrequenz-Verstärkungsdifferenzinformation zum Erzeugen von Hochfrequenz-Verstärkungsdifferenzinformation-Kodierdaten;
einer Multiplexeinrichtung (20) zum Multiplexen wenigstens der Niederfrequenz-Kodierdaten und der Hochfrequenz-Verstärkungsdifferenzinformation-Kodierdaten zum Ausgeben der Multiplexdaten als komprimierte Daten;
einer Gruppierungsinformation-Erzeugungseinrichtung (15) zum Erzeugen von Hochfrequenz-Gruppierungsverstärkungsinformation jeder Gruppe und Erzeugen einer Hochfrequenz-Verstärkungsgruppierungsinformation über ein Gruppierungsverfahren durch ein Gruppieren der Hochfrequenz-Verstärkungsinformation, die in jedem Unterband bei einem zuvor festgelegten Zeitintervall durch mehrere Gruppen in einer Zeitrichtung erzeugt wurde,
wobei die Hochfrequenz-Verstärkungsdifferenzinformation-Erzeugungseinrichtung dazu geeignet ist, die Hochfrequenz-Verstärkungsdifferenzinformation durch ein Einholen eines Differenzwerts mit einer Hochfrequenz-Gruppierungsverstärkungsinformation bei einem angrenzenden Niederfrequenz-Unterband an einer entsprechenden Zeitposition zu erzeugen, und die Multiplexeinrichtung ferner dazu geeignet ist, die Hochfrequenz-Verstärkungsgruppierungsinformation zu multiplexen;wobei die Niederfrequenz-Referenzverstärkungswertinformation-Erzeugungseinrichtung dazu geeignet ist, Niederfrequenz-Referenzverstärkungswertinformation über ein ausgewähltes Erzeugungsverfahren mit der Niederfrequenz-Referenzverstärkungswertinformation zu erzeugen, indem sie adaptiv entweder das Verfahren zum Erzeugen der Niederfrequenz-Referenzverstärkungswertinformation aus dem gesamten Niederfrequenz-Unterbandsignal oder ein Verfahren zum Erzeugen der Niederfrequenz-Referenzverstärkungswertinformation durch Gruppen aus dem Niederfrequenz-Unterbandsignal auf der Grundlage der Hochfrequenz-Verstärkungsgruppierungsinformation auswählt, und die Multiplexeinrichtung ferner dazu geeignet ist, die Niederfrequenz-referenzverstärkungswertinformation-Auswahlinformation zu multiplexen.
wobei die Niederfrequenz-Referenzverstärkungswertinformation-Erzeugungseinrichtung (16) das Verfahren zum Erzeugen der Niederfrequenz-Referenzverstärkungswertinformation aus dem gesamten Niederfrequenz-Unterbandsignal oder das Verfahren zum Erzeugen der Niederfrequenz-Referenzverstärkungswertinformation durch Gruppen aus dem Niederfrequenz-Unterbandsignal auf der Grundlage eines Quantisierungsfehlers des Niederfrequenz-Unterbandsignals auswählt.
wobei die Niederfrequenz-Referenzinformation-Erzeugungseüzrichtung (16) das Verfahren zum Erzeugen der Niederfrequenz-Referenzverstärkungswertinformation aus dem gesamten Niederfrequenz-Unterbandsignal oder das Verfahren zum Erzeugen der Niederfrequenz-Referenzverstärkungswertinformation durch Gruppen aus dem Niederfrequenz-Unterbandsignal zum Reduzieren einer Kodemenge der Hochfrequenz-Verstärkungsdifferenzinformation auswählt.
einer Quantisierungsstufeninformation-Erzeugungseinrichtung (18) zum Erzeugen von Quantisierungsstufeninformation zur Zeit des Quantisierens der Hochfrequenz-Verstärkungsdifferenzinformation auf der Grundlage der Hochfrequenz-Verstärkungsdifferenzinformation,
wobei die Multiplexeinrichtung (20) ferner die Quantisierungsstufeninformation multiplext.einer Glättungsverfahren-Auswahlinformation-Erzeugungseinrichtung (14) zum Erzeugen einer Glättungverfahrenauswahlinformation über ein Verfahren zum Glätten des an einer Dekoderseite in einer Zeitrichtung auf der Grundlage der Hochfrequenz-Verstärkungsinformation erzeugten Hochfrequenz-Unterbandsignals,
wobei die Multiplexeinrichtung (20) ferner die Glättungsverfahren-auswahlinformation multiplext.Partitionieren des Zeitreihensignals in mehrere Unterbänder und Erzeugen eines Niederfrequenz-Unterbandsignals mit mehreren Niederfrequenz-Unterbändern und eines Hochfrequenz-Unterbandsignals mit mehreren Hochfrequenz-Unterbändern;
Quantisieren und Kodieren des Niederfrequenz-Unterbandsignals zum Erzeugen von Niederfrequenz-Kodierdaten;
Erzeugen einer Hochfrequenz-Verstärkungsinformation durch Erzeugen eines neuen Hochfrequenz-Unterbandsignals aus dem Niederfrequenz-Unterbandsignal und Steuern der Verstärkung des neuen Hochfrequenz-Unterbandsignals, das aus dem Niederfrequenz-Unterbandsignal erzeugt wurde, mithilfe des Verstärkungswerts der Hochfrequenz-Information für jedes Unterband an einem zuvor festgelegten Zeitintervall;
Erzeugen einer Niederfrequenz-Referenzverstärkungswertinformation auf der Grundlage wenigstens des Niederfrequenz-Unterbandsignals;
Erzeugen einer Hochfrequenz-Verstärkungsdifferenzinformation durch Einholen eines Differenzwerts zwischen der Hochfrequenz-Verstärkungsinformation, die in jedem Unterband bei einem zuvor festgelegten Zeitintervall erzeugt wurde, und der Hochfrequenz-Verstärkungsinformation eines angrenzenden Niederfrequenz-Unterbands an einer entsprechenden Zeitposition, die einem angrenzenden Niederfrequenz-Unterband entspricht, und Einholen eines Differenzwerts zwischen einer Hochfrequenz-Verstärkungsinformation eines Niedrigstfrequenz-Unterbands in dem Hochfrequenz-Unterbandsignal und der Niederfrequenz-Referenzverstärkungswertinformation;
Quantisieren und Kodieren der Hochfrequenz-Verstärkungsdifferenzinformation zum Erzeugen von Hochfrequenz-Verstärkungsdifferenzinformation-Kodierdaten;
Multiplexen wenigstens der Niederfrequenz-Kodierdaten and der Hochfrequenz-Verstärkungsdifferenzinformation-Kodierdaten zum Ausgeben der multiplexten Daten als komprimierte Daten;
Erzeugen einer Hochfrequenz-Gruppierungsverstärkungsinformation jeder Gruppe und Erzeugen von Hochfrequenz-Verstärkungsgruppierungsinformation über ein Gruppierungsverfahren durch Gruppieren der Hochfrequenz-Verstärkungsinformation, die in jedem Unterband bei einem zuvor festgelegten Zeitintervall erzeugt wurde, zu mehreren Gruppen in einer Zeitrichtung,
Erzeugen der Hochfrequenz-Verstärkungsdifferenzinformation durch Einholen eines Differenzwerts mit einer Hochfrequenz-Gruppierungsverstärkungsinformation an einem angrenzenden Niederfrequenz-Unterband an einer entsprechenden Zeitposition und ferner Multiplexen der Hochfrequenz-Verstärkungsgruppierungsinformation;
wobei die Niederfrequenz-Referenzverstärkungswertinformation über ein ausgewähltes Erzeugungsverfahren dadurch erzeugt wird, dass adaptiv entweder das Verfahren zum Erzeugen der Niederfrequenz-Referenzverstärkungswertinformation aus dem gesamten Niederfrequenz-Unterbandsignal oder ein Verfahren zum Erzeugen der Niederfrequenz-Referenzverstärkungswertinformation durch Gruppen aus dem Niederfrequenz-Unterbandsignal auf der Grundlage der Hochfrequenz-Verstärkungsgruppierungsinformation ausgewählt wird und die Niederfrequenz-Referenzverstärkungswertauswahlinformation gemultiplext wird.eine Demultiplexer-Einrichtung (61) zum Demultiplexen der komprimierten Daten zum Erzeugen von Niederfrequenz-Kodierdaten und Hochfrequenz-Verstärkungsdifferenzkodierdaten;
eine Niederfrequenz-Dekodiereinrichtung (62) zum Dekodieren und Dequantisieren der Niederfrequenz-Kodierdaten zum Erzeugen eines Niederfrequenz-Unterbandsignals;
eine Niederfrequenz-Referenzverstärkungswertinformation-Erzeugungseinrichtung (63) zum Erzeugen von Niederfrequenz-Referenzverstärkungswertinformation auf der Grundlage wenigstens des Niederfrequenz-Unterbandsignals;
eine Hochfrequenz-Verstärkungsdifferenzinformation-Erzeugungseinrichtung (64) zum Erzeugen von Hochfrequenz-Verstärkungsdifferenzinformation von jedem Unterband an einem zuvor festgelegten Zeitintervall durch Dekodieren und Dequantisieren der Hochfrequenz-Verstärkungsdifferenzinformation-Kodierdaten;
eine Hochfrequenz-Verstärkungsinformation-Erzeugungseinrichtung (65) zum Erzeugen von Hochfrequenz-Verstärkungsinformation auf der Grundlage einer Hochfrequenz-Verstärkungsdifferenzinformation eines angrenzenden Unterbands an einer entsprechenden Zeitposition und Erzeugen einer Hochfrequenz-Verstärkungsinformation auf der Grundlage der Niederfrequenz-Referenzverstärkungswertinformation in einem Niedrigstfrequenz-Unterband der Hochfrequenz-Unterbandsignale;
eine Hochfrequenz-Erzeugungseinrichtung (66) zum Erzeugen des Hochfrequenz-Unterbandsignals aus dem Niederfrequenz-Unterbandsignal und Steuern der Verstärkung des Hochfrequenz-Unterbandsignals auf der Grundlage der Hochfrequenz-Verstärkungsinformation; und
eine Synthesizer-Einrichtung (67) zum Zusammensetzen des Niederfrequenz-Unterbandsignals und des Hochfrequenz-Unterbandsignals mit einer gesteuerten Verstärkung zum Ausgeben der zusammengesetzten Signale als ein Zeitreihensignal;
wobei die komprimierten Daten Glättungsverfahren-Auswahlinformation über ein Verfahren zum Glätten des Hochfrequenz-Unterbandsignals in einer Zeitrichtung aufweisen; undwobei die Hochfrequenz-Erzeugungseinrichtung die Verstärkung des Hochfrequenz-Unterbandsignals steuert, das aus dem Niederfrequenz-Unterbandsignal auf der Grundlage der Hochfrequenz-Verstärkungsinformation und der Glättungsverfahren-Auswahlinformation erzeugt wurde.
wobei die Hochfrequenz-Verstärkungsdifferenzinformation-Erzeugungseinrichtung (64) die Hochfrequenz-Verstärkungsdifferenzinformation durch Unterbänder und durch Gruppen durch ein Dekodieren und Dequantisieren der Hochfrequenz-Verstärkungsdifferenzinformations-Kodierdaten erzeugt;
die Hochfrequenz-Verstärkungsinformation-Erzeugungseinrichtung (65) eine Hochfrequenz-Verstärkungsinformation auf der Grundlage einer Hochfrequenz-Verstärkungsdifferenzinformation an einem angrenzenden Niederfrequenz-Unterband an einer entsprechenden Zeitposition erzeugt und Hochfrequenz-Verstärkungsinformation auf der Grundlage der Niederfrequenz-Referenzverstärkungswertinformation eines Niedrigstfrequenz-Unterbandes in dem Hochfrequenz-Unterbandsignal erzeugt; und
die Hochfrequenz-Erzeugungseinrichtung (66) das Hochfrequenz-Unterbandsignal aus dem Niederfrequenz-Unterbandsignal erzeugt und die Verstärkung des Hochfrequenz-Unterbandsignals auf der Grundlage der Hochfrequenz-Verstärkungsinformation steuert.
wobei die komprimierten Audiodaten eine Niederfrequenz-Referenzverstärkungswert-Auswahlinformation über ein Verfahren zum Erzeugen der Niederfrequenz-Referenzverstärkungswert-Auswahlinformation aufweist; und
wobei die Niederfrequenz-Referenzverstärkungswertinformation-Erzeugungseinrichtung (63) ein Verfahren zum Erzeugen von Niederfrequenz-Referenzverstärkungswertinformation aus dem gesamten Niederfrequenz-Unterbandsignal auf der Grundlage der Niederfrequenz-Referenzverstärkungswert-Auswahlinformation oder ein Verfahren zum Erzeugen der Niederfrequenz-Referenzverstärkungswertinformation jeder Gruppe aus dem Niederfrequenz-Unterbandsignal auf der Grundlage der Hochfrequenz-Verstärkungsgruppierungsinformation auswählt.
Demultiplexen der komprimierten Daten zum Erzeugen von Niederfrequenz-Kodierdaten und Hochfrequenz-Verstärkungsdifferenz-Kodierdaten;
Dekodieren und Dequantisieren der Niederfrequenz-Kodierdaten zum Erzeugen des Niederfrequenz-Unterbandsignals;
Erzeugen einer Niederfrequenz-Referenzverstärkungswertinformation auf der Grundlage wenigstens des Niederfrequenz-Unterbandsignals;
Erzeugen einer Hochfrequenz-Verstärkungsdifferenzinformation jedes Unterbands an einem zuvor festgelegten Zeitintervall durch Dekodieren und Dequantisieren der Hochfrequenz-Verstärkungsdifferenzinformation-Kodierdaten;
Erzeugen einer Hochfrequenz-Verstärkungsinformation auf der Grundlage einer Hochfrequenz-Verstärkungsdifferenzinformation eines angrenzenden Unterbands an einer entsprechenden Zeitposition und Erzeugen einer Hochfrequenz-Verstärkungsinformation auf der Grundlage der Niederfrequenz-Referenzverstärkungswertinformation eines Niedrigstfrequenz-Unterbands in dem Hochfrequenz-Unterbandsignal;
Erzeugen des Hochfrequenz-Unterbandsignals aus dem Niederfrequenz-Unterbandsignal und Steuern der Verstärkung des Hochfrequenz-Unterbandsignals auf der Grundlage der Hochfrequenz-Verstärkungsinformation;
Zusammensetzen des Niederfrequenz-Unterbandsignals und des Hochfrequenz-Unterbandsignals mit einer gesteuerten Verstärkung zum Ausgeben der zusammengesetzten Signale als ein Zeitreihensignal;
wobei die komprimierten Daten eine Glättungsverfahren-Auswahlinformation über ein Verfahren zum Glätten des Hochfrequenz-Unterbandsignals in einer Zeitrichtung aufweisen; undwobei die Hochfrequenz-Erzeugungseinrichtung die Verstärkung des Hochfrequenz-Unterbandsignals steuert, das aus dem Niederfrequenz-Unterbandsignal auf der Grundlage der Hochfrequenz-Verstärkungsinformation und der Glättungsverfahren-Auswahlinformation erzeugt wurde.
des moyens de partitionnement (11) pour partitionner le signal de série temporelle en une pluralité de sous-bandes afin de générer un signal de sous-bande basse fréquence incluant une pluralité de sous-bandes basse fréquence et un signal de sous-bande haute fréquence incluant une pluralité de sous-bandes haute fréquence ;
des moyens de codage basse fréquence (12) pour quantifier et coder le signal de sous-bande basse fréquence afin de générer des données de codage basse fréquence ;
des moyens de génération d'informations de gain haute fréquence (13) pour générer des informations de gain haute fréquence en générant un nouveau signal de sous-bande haute fréquence à partir du signal de sous-bande basse fréquence et commander le gain du nouveau signal de sous-bande haute fréquence généré à partir du signal de sous-bande basse fréquence en utilisant la valeur de gain des informations haute fréquence pour chaque sous-bande à un intervalle de temps prédéterminé ;
des moyens de génération d'informations de valeur de gain de référence basse fréquence (16) pour générer des informations de valeur de gain de référence basse fréquence sur la base d'au moins le signal de sous-bande basse fréquence ;
des moyens de génération d'informations de différence de gain haute fréquence (17) pour générer des informations de différence de gain haute fréquence en acquérant une valeur de différence entre les informations de gain haute fréquence générées dans chaque sous-bande à un intervalle de temps prédéterminé et les informations de gain haute fréquence d'une sous-bande basse fréquence adjacente à une position temporelle correspondante correspondant à une sous-bande basse fréquence adjacente, et acquérir une valeur de différence entre des informations de gain haute fréquence d'une sous-bande de fréquence la plus basse dans le signal de sous-bande haute fréquence et les informations de valeur de gain de référence basse fréquence ;
des moyens de codage d'informations de différence de gain haute fréquence (19) pour quantifier et coder les informations de différence de gain haute fréquence afin de générer des données de codage d'informations de différence de gain haute fréquence ;
des moyens de multiplexage (20) pour multiplexer au moins les données de codage basse fréquence et les données de codage d'informations de différence de gain haute fréquence afin de sortir les données multiplexées comme données compressées ;
des moyens de génération d'informations de groupage (15) pour générer des informations de gain de groupage haute fréquence de chaque groupe et générer des informations de groupage de gain haute fréquence concernant un procédé de groupage en groupant les informations de gain haute fréquence générées dans chaque sous-bande à un intervalle de temps prédéterminé par une pluralité de groupes dans une direction temporelle,
dans lequel les moyens de génération d'informations de différence de gain haute fréquence sont adaptés pour générer les informations de différence de gain haute fréquence en acquérant une valeur de différence avec des informations de gain de groupage haute fréquence au niveau d'une sous-bande basse fréquence adjacente à une position temporelle correspondante, et les moyens de multiplexage sont en outre adaptés pour multiplexer les informations de groupage de gain haute fréquence ;dans lequel les moyens de génération d'informations de valeur de gain de référence basse fréquence sont adaptés pour générer des informations de valeur de gain de référence basse fréquence concernant un procédé de génération sélectionné avec les informations de valeur de gain de référence basse fréquence en sélectionnant adaptativement soit le procédé de génération d'informations de valeur de gain de référence basse fréquence à partir du signal de sous-bande basse fréquence entier, soit un procédé de génération des informations de valeur de gain de référence basse fréquence par groupes à partir du signal de sous-bande basse fréquence sur la base des informations de groupage de gain haute fréquence, et les moyens de multiplexage sont en outre adaptés pour multiplexer les informations de sélection de valeur de gain de référence basse fréquence.
dans lequel les moyens de génération d'informations de valeur de gain de référence basse fréquence (16) sélectionnent un entre le procédé de génération des informations de valeur de gain de référence basse fréquence à partir du signal de sous-bande basse fréquence entier et le procédé de génération des informations de valeur de gain de référence basse fréquence par groupes à partir du signal de sous-bande basse fréquence, sur la base d'une erreur de quantification du signal de sous-bande basse fréquence.
dans lequel les moyens de génération d'informations de référence basse fréquence (16) sélectionnent un entre le procédé de génération des informations de valeur de gain de référence basse fréquence à partir du signal de sous-bande basse fréquence entier et le procédé de génération des informations de valeur de gain de référence basse fréquence par groupes à partir, du signal de sous-bande basse fréquence afin de réduire une quantité de code des informations de différence de gain haute fréquence.
des moyens de génération d'informations d'échelon de quantification (18) pour générer des informations d'échelon de quantification au moment de la quantification des informations de différence de gain haute fréquence sur la base des informations de différence de gain haute fréquence,
dans lequel les moyens de multiplexage (20) multiplexent en outre les informations d'échelon de quantification.des moyens de génération d'informations de sélection de procédé de lissage (14) pour générer des informations de sélection de procédé de lissage concernant un procédé de lissage du signal de sous-bande haute fréquence généré au niveau d'un côté de décodage dans une direction temporelle sur la base des informations de gain haute fréquence,
dans lequel les moyens de multiplexage (20) multiplexent en outre les informations de sélection de procédé de lissage.partitionner le signal de série temporelle en une pluralité de sous-bandes et générer un signal de sous-bande basse fréquence incluant une pluralité de sous-bandes basse fréquence et un signal de sous-bande haute fréquence incluant une pluralité de sous-bandes haute fréquence ;
quantifier et coder le signal de sous-bande basse fréquence afin de générer des données de codage basse fréquence ;
générer des informations de gain haute fréquence en générant un nouveau signal de sous-bande haute fréquence à partir du signal de sous-bande basse fréquence et commander le gain du nouveau signal de sous-bande haute fréquence généré à partir du signal de sous-bande basse fréquence en utilisant la valeur de gain des informations haute fréquence pour chaque sous-bande à un intervalle de temps prédéterminé ;
générer des informations de valeur de gain de référence basse fréquence sur la base d'au moins le signal de sous-bande basse fréquence ;
générer des informations de différence de gain haute fréquence en acquérant une valeur de différence entre les informations de gain haute fréquence générées dans chaque sous-bande à un intervalle de temps prédéterminé et les informations de gain haute fréquence d'une sous-bande basse fréquence adjacente à une position temporelle correspondante correspondant à une sous-bande basse fréquence adjacente, et acquérir une valeur de différence entre des informations de gain haute fréquence d'une sous-bande de fréquence la plus basse dans le signal de sous-bande haute fréquence et les informations de valeur de gain de référence basse fréquence ;
quantifier et coder les informations de différence de gain haute fréquence afin de générer des données de codage d'informations de différence de gain haute fréquence ;
multiplexer au moins les données de codage basse fréquence et les données de codage d'informations de différence de gain haute fréquence afin de sortir les données multiplexées comme données compressées ;
générer des informations de gain de groupage haute fréquence de chaque groupe et générer des informations de groupage de gain haute fréquence concernant un procédé de groupage en groupant les informations de gain haute fréquence générées dans chaque sous-bande à un intervalle de temps prédéterminé par une pluralité de groupes dans une direction temporelle,
générer les informations de différence de gain haute fréquence en acquérant une valeur de différence avec des informations de gain de groupage haute fréquence au niveau d'une sous-bande basse fréquence adjacente à une position temporelle correspondante, et multiplexer en outre les informations de groupage de gain haute fréquence ;
dans lequel les informations de valeur de gain de référence basse fréquence concernant un procédé de génération sélectionné sont générées en sélectionnant adaptativement soit le procédé de génération d'informations de valeur de gain de référence basse fréquence à partir du signal de sous-bande basse fréquence entier, soit un procédé de génération des informations de valeur de gain de référence basse fréquence par groupes à partir du signal de sous-bande basse fréquence sur la base des informations de groupage de gain haute fréquence, et les informations de sélection de valeur de gain de référence basse fréquence sont multiplexées.des moyens de démultiplexage (61) pour démultiplexer les données compressées afin de générer des données de codage basse fréquence et des données de codage de différence de gain haute fréquence ;
des moyens de décodage basse fréquence (62) pour décoder et déquantifier les données de codage basse fréquence afin de générer un signal de sous-bande basse fréquence ;
des moyens de génération d'informations de valeur de gain de référence basse fréquence (63) pour générer des informations de valeur de gain de référence basse fréquence sur la base d'au moins le signal de sous-bande basse fréquence ;
des moyens de génération d'informations de différence de gain haute fréquence (64) pour générer des informations de différence de gain haute fréquence de chaque sous-bande à un intervalle de temps prédéterminé en décodant et en déquantifiant les données de codage d'informations de différence de gain haute fréquence ;
des moyens de génération d'informations de gain haute fréquence (65) pour générer des informations de gain haute fréquence sur la base d'informations de différence de gain haute fréquence d'une sous-bande adjacente à une position temporelle correspondante et générer des informations de gain haute fréquence sur la base des informations de valeur de gain de référence basse fréquence dans une sous-bande de fréquence la plus basse à partir des signaux de sous-bande haute fréquence ;
des moyens de génération haute fréquence (66) pour générer le signal de sous-bande haute fréquence à partir du signal de sous-bande basse fréquence et commander le gain du signal de sous-bande haute fréquence sur la base des informations de gain haute fréquence ; et
des moyens de synthèse (67) pour synthétiser le signal de sous-bande basse fréquence et le signal de sous-bande haute fréquence ayant un gain commandé afin de sortir les signaux synthétisés comme un signal de série temporelle ;
dans lequel les données compressées incluent des informations de sélection de procédé de lissage concernant un procédé de lissage du signal de sous-bande haute fréquence dans une direction temporelle ; etdans lequel les moyens de génération haute fréquence commandent le gain du signal de sous-bande haute fréquence généré à partir du signal de sous-bande basse fréquence sur la base des informations de gain haute fréquence et des informations de sélection de procédé de lissage.
dans lequel les moyens de génération d'informations de différence de gain haute fréquence (64) génèrent les informations de différence de gain haute fréquence par sous-bandes et par groupes en décodant et en déquantifiant les données de codage d'informations de différence de gain haute fréquence ;
les moyens de génération d'informations de gain haute fréquence (65) génèrent des informations de gain haute fréquence sur la base d'informations de différence de gain haute fréquence au niveau d'une sous-bande basse fréquence adjacente à une position temporelle correspondante et génèrent des informations de gain haute fréquence sur la base des informations de valeur de gain de référence basse fréquence d'une sous-bande de fréquence la plus basse dans le signal de sous-bande haute fréquence ; et
les moyens de génération haute fréquence (66) génèrent le signal de sous-bande haute fréquence à partir du signal de sous-bande basse fréquence et commandent le gain du signal de sous-bande haute fréquence sur la base des informations de gain haute fréquence.
dans lequel les données audio compressées incluent des informations de sélection de valeur de gain de référence basse fréquence concernant un procédé de génération des informations de sélection de valeur de gain de référence basse fréquence ; et
dans lequel les moyens de génération d'informations de valeur de gain de référence basse fréquence (63) sélectionnent un entre un procédé de génération d'informations de valeur de gain de référence basse fréquence à partir du signal de sous-bande basse fréquence entier sur la base des informations de sélection de valeur de gain de référence basse fréquence et un procédé de génération des informations de valeur de gain de référence basse fréquence de chaque groupe à partir du signal de sous-bande basse fréquence sur la base des informations de groupage de gain haute fréquence.
démultiplexer les données compressées afin de générer des données de codage basse fréquence et des données de codage de différence de gain haute fréquence ;
décoder et déquantifier les données de codage basse fréquence afin de générer un signal de sous-bande basse fréquence ;
générer des informations de valeur de gain de référence basse fréquence sur la base d'au moins le signal de sous-bande basse fréquence ;
générer des informations de différence de gain haute fréquence de chaque sous-bande à un intervalle de temps prédéterminé en décodant et en déquantifiant les données de codage d'informations de différence de gain haute fréquence ;
générer des informations de gain haute fréquence sur la base d'informations de différence de gain haute fréquence d'une sous-bande adjacente à une position temporelle correspondante et générer des informations de gain haute fréquence sur la base des informations de valeur de gain de référence basse fréquence d'une sous-bande de fréquence la plus basse dans le signal de sous-bande haute fréquence ;
générer le signal de sous-bande haute fréquence à partir du signal de sous-bande basse fréquence et commander le gain du signal de sous-bande haute fréquence sur la base des informations de gain haute fréquence ;
synthétiser le signal de sous-bande basse fréquence et le signal de sous-bande haute fréquence ayant un gain commandé afin de sortir les signaux synthétisés comme un signal de série temporelle ;
avec les données compressées incluant des informations de sélection de procédé de lissage concernant un procédé de lissage du signal de sous-bande haute fréquence dans une direction temporelle ; et
les moyens de génération haute fréquence commandant le gain du signal de sous-bande haute fréquence généré à partir du signal de sous-bande basse fréquence sur la base des informations de gain haute fréquence et des informations de sélection de procédé de lissage.
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This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
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